Mrs Teo said the right thing is to share the investment costs between the Government, CAG and those who will use the facilities.

"The Government will look at this from the perspective of how it benefits Singaporeans and Singapore as a whole," she said.

In charging airlines and travellers, one has to be mindful that Changi Airport must remain competitive in an increasingly challenging environment.

The project aims to cement Singapore's position as a key hub for regional and global traffic, amid fierce competition from rival airports in Hong Kong, South Korea and elsewhere.

The development of the 1,000ha Changi East site - about three-quarters the size of the current airport premises - includes the construction of T5, a third runway, new taxiways and plane parking areas, as well as cargo facilities.

In an earlier interview with The Straits Times, Mr Liew had suggested that one option was for the Government to foot the entire bill, leaving his team to run the airport.

Explaining the rationale for co-funding, Mrs Teo who is also Senior Minister of State for Finance, said: "Fiscal requirements for the Government, as a whole, will become more significant.

"We already know that we are going to have to spend more on healthcare. We have a lot of social programmes which we think are important. We want to continue to invest in education for our people and a large part of it is also the SkillsFuture piece."

Still, the Government knows how vital the aviation sector is and will factor this in when funding decisions are made, she said.

"If you look just at the number of people working at the airport, it is quite modest: 77,000, 3 per cent of GDP," she said. "But if you look at it through a broader lens and ask which are all the other sectors that will be quite hurt if your air hub was lousy, then you would add tourism, finance, retail; and if you add all of those sectors, it is another 16 per cent of the economy, another half a million people...

"Then you say the externalities are very big. Therefore, when you develop Changi East and it's a massive investment, it's reasonable for the Government to bear a part of the costs."

Pressed further on what this could amount to, she said: "The Government is sensible."

Citing the MRT system as an example, she pointed out that the Government funded all the infrastructure and first set of rolling stock which accounted for about 90 per cent of the total start-up costs.

Terence Fan, a transport specialist from the Singapore Management University, said the Government should consider some private-sector involvement in the Changi East project.

"When the private sector is involved, whoever pays is keen to ensure that resources are used efficiently. This helps the Government get the best bang for its buck," said Associate Professor Fan.

karam@sph.com.sg

This article by The Straits Times was published in MyPaper, a free, bilingual newspaper published by Singapore Press Holdings.